The present invention relates to a new and improved construction of a vertical sensor.
In its more particular aspects, the present invention specifically relates to a new and improved construction of a vertical sensor containing a container filled by a light absorbing liquid and an air bubble enclosed therein. The air bubble is displaced upon deviation of the container position from its vertical indicating position. Light barrier means are disposed on opposite sides of the container and respond to the displacement of the air bubble.
North-seeking gyro devices as well as other apparatus require vertical disposition for their faultless function. It is known to effect vertical alignment of a device or apparatus by means of a mercury-filled container wherein electrical contact is made upon deviation of the container position from the vertical position. A finite separating distance must be present between the mercury surface and a contact which is not immersed into the mercury in the vertical container position. Mercury switches of this type thus respond only to coarse deviations from the vertical in the order of magnitude of some degrees. Such mercury switches, then, can supply a signal which either indicates the deviation from the vertical position or causes automatic re-alignment.
An apparatus of this type such as known, for example, from U.S. Pat. No. 4,154,000, granted May 15, 1979, and directed to remote sensing of horizontal alignment, contains a cylindrical container which is filled by a transparent liquid including an air bubble. A plural number of light sources and light sensors are arranged on respective opposite sides of the container in a manner such that the light emitted by the light sources, impinges upon the light sensors due to light refraction by the liquid-filled container, i.e. in the absence of the air bubble. The arrangement is such that there are indicated a zero position of the air bubble and its deviation from the zero position as well as the direction of the deviation in order to effect, for instance, horizontal positioning of a trailer or mobile home.
U.S. Pat. No. 4,110,609, granted Aug. 29, 1978, relates to a tilt limiting detecting apparatus containing, among other things, a vessel which is rectangular in section and filled by an opaque liquid including an air bubble. Light sources and light sensors are arranged on respective opposite sides close to the ends of the container. The light sensors produce an output signal in the presence of the air bubble which migrates towards corresponding ones of the container ends upon deflections of the container from its horizontal position.
U.S. Pat. No. 3,813,556, granted on May 28, 1974, is also concerned with tilt limit detecting apparatus in connection with, for example, aircraft landing systems. This apparatus contains, among other things, a curved container which is rectangular in cross-section and filled by an opaque liquid including an air bubble. In a zero position of the air bubble, a light source and a light sensor are disposed on respective opposite sides of the container. Additionally, and at a lateral spacing greater than the width of the air bubble, a further light source and a further light sensor can be provided for determining the direction of a deflection of the container from the horizontal position.
From U.S. Pat. No. 4,517,750, granted May 21, 1985, there are known a vertical indicating method and device, particularly in connection with a compound pendulum which contains a rotatably journalled rotor in a liquid-filled housing. The housing is provided with a bellows to compensate temperature-caused changes in the liquid volume. There is thus provided therein a container which is completely filled by the liquid, and liquid volume compensating means are arranged within the container in order to maintain substantially constant the pressure prevailing in the interior of the container in the event of temperature changes.
In the aforementioned vertical sensors the liquid including the air bubble is tightly enclosed into the container so that the air bubble is subject to changes in shape as a result of temperature changes as such but also due to the volume changes in the liquid connected therewith. Thus, in the event of a temperature increase, the volume of the air bubble may be reduced to an extent such that there is caused thereby, at the sensor of the light barrier means, an intensity change of the light impinging thereupon and, in turn, simulated a deviation of the container from its vertical indicating position.